Abstract:Based on the operational real-time typhoon data of National Meteorological Centre and other sources of observations including automatic station and satellite images, the main characteristics of typhoon activities in Western North Pacific and the South China Sea in 2021, including influential tracks, strength, wind and rainfall, are analyzed and reviewed. It is found that in 2021, the genesis region was obviously westward, with five typhoons generated in the South China Sea. The overall strengths of the typhoons were weaker than normal, and six typhoons experienced rapid strengthening activities, among which Typhoon Chanthu increased to 40 m·s-1 within 24 hours, which was rare in the past 30 year. Six typhoons made landfall in China and the other two affected coastal areas. The forecast error analysis shows that the main strength forecast error was due to the rapid strengthening cases, while the track forecast error was mainly caused by the sharp turning of typhoons. Under the weak steering flow, the northward movement of Typhoon In-Fa after slowing down was related to the influence of upper-tropospheric cold low. The increase of offshore deep convection caused by land-sea thermal difference and local convergence could be the main reason for the offshore rapid strengthening of Typhoon Cempaka. Under the background of the obvious adjustment of the subtropical high, Typhoon Chanthu dwelled over the northern part of the East China Sea for three days bringing obvious rainfall and gale winds to the East China.